Efforts in developing and testing new drugs for the treatment of the cognitive impairment associated with Alzheimer's disease represent a major programmatic activity of NIA but are now hindered by the lack of access of many investigators to animal testing facilities. The present paucity of any compounds which can uniformly slow or reverse the progression of the disease or ameliorate the symptoms requires that every effort be made to facilitate the development and testing of new and compounds. The need to develop compounds for other aging-related diseases such as osteoporosis is also apparent. However, there are still gaps in our overall effort to facilitate the development and testing of new compounds. Specifically, resources are needed by investigators who are developing new compounds so that the potential adverse toxicological activity of the compounds can be evaluated before they can be taken into clinical trials. This is a very expensive process and is beyond the resources of almost all investigators. The purpose of this contract is to evaluate acute and chronic toxicity in rodents and dogs of drugs which are proposed to have potential use in the treatment of Alzheimer's disease and other aging-related diseases. The data generated from those studies will be used as part of the filing of an Investigational New Drug Application to the Food and Drug Administration in order to receive approval to use the drugs in humans. This will expand drug development efforts for Alzheimer's disease and other aging-related diseases to a larger and more diverse group of investigators.